Q1: Multiple effect evaporators are commonly used in the manufacture of
P. Paper Q. Superphosphate
R. Sugar S. Fats

ANS:C - P and S

Multiple effect evaporators are a type of evaporator system used in industries for concentrating solutions. The term "multiple effect" refers to the fact that these evaporators consist of multiple stages or effects, each utilizing the vapor generated from the previous stage to heat the next one, thereby increasing energy efficiency. Here's how it works:

1. Initial Heating Stage (First Effect): In the first effect, the solution to be concentrated is heated by steam or another heat source. As it heats up, some of the water evaporates, leaving behind a more concentrated solution.
2. Subsequent Effects: The vapor generated in the first effect is used to heat the solution in the second effect. This vapor condenses on the heat exchanger surfaces in the second effect, transferring its heat to the solution, causing more evaporation. This process continues through multiple effects, with each effect operating at a lower pressure and temperature than the previous one.
3. Energy Efficiency: By using the vapor from the previous effect to heat the next one, multiple effect evaporators significantly reduce the amount of external heat needed to concentrate the solution. This makes them much more energy-efficient compared to single-effect evaporators.
4. Final Concentration: The solution is progressively concentrated as it passes through each effect. The concentrated solution from the final effect is typically sent to a crystallizer or another unit operation for further processing, depending on the industry and the desired product.